1. Figure 5: Florida Incidence Mean by Year
The Impact of Temperature and pH Change on Vibrio Infection in the State of Florida
Rachael Curtis, MS, H. Anwar Ahmad, PhD and Luma Akil, PhD
Jackson State University, Jackson, Mississippi USA
Statistical Analysis
The emergence of infectious vector-borne and zoonotic diseases may be affected by population density, geographic distribution, or climate change.
The Gulf States are well known for the variation in temperature throughout the year. These extremes have adversely affected water quality, which can enhance susceptibility to water and foodborne diseases such as Hepatitis A, salmonellosis, campylobacteriosis , and vibriosis.
Currently, the state of Florida has the highest incidence rates of Vibrio of all US states.
pH affects most chemical and biological processes in water. It is one of the most important environmental factors influencing the distribution of species in aquatic habitats. Most bacteria are pH-sensitive, therefore they may proliferate faster in pH-favorable aquatic environments.
Abstract
Regression analysis was performed using SAS 9.4 where temperature and pH were used as independent (classification) variables and Vibriosis outbreaks as dependent (response) variables.
The association between difference between the incidence in Vibrio cases in relation to temperature and pH during the study period was analyzed using this approach.
To determine the seasonal relation between temperature, pH, and Vibrio cases a general linear model (GLM) was used.
The harvest and consumption of raw oysters, shrimp, crabs, and other shellfish in the U.S. Gulf States, particularly Florida, have been reported to increase the spread of foodborne pathogens, such as Vibrio. Temperature and pH are considered to affect the incidence rates of foodborne diseases including Vibrio. Weekly data for Vibrio outbreaks in Florida were retrieved from Centers for Disease Control (CDC) from ; temperature data were collected from Southeast Regional Climate Center under National Oceanic and Atmospheric Administration (NOAA); and pH data were collected from the Centralized Data Management Office at the National Estuarine Research Reserve. Various data were analyzed from 2009 to 2011 using analysis of variance and regression model in SAS 9.4. Results indicated a seasonal trend in Vibrio infections (p<0.001). A positive correlation was found between temperature and Vibrio infections, however, there was no correlation between pH and Vibrio incidence. In this study, it was determined that for every 14.28° F temperature increase, there was one new case of Vibriosis in Florida. Furthermore, 17% of all Vibrio infections were directly attributed to temperature increases. Although there was no association between the incidence of Vibrio and pH, temperature changes are likely to increase the frequency of bacterial, viral, and protozoan pathogens in the environment. Temperature increases, and possibly other environmental factors, enable marine species to proliferate at a faster rate, hence, influencing the prevalence of infection.   a
Results b
Figure 4: Incidence Rates by Season
A positive correlation was found between the temperature and Vibrio outbreaks in Florida (R2=0.17) (Fig 2),
Furthermore, results indicated that for every 9.84°C temperature increase, there is one new case of Vibriosis in Florida (y = 0.07x ).
However, a very weak correlation was found between pH and Vibriosis (R2=0.0051).
A cluster effect was found between the pH range of , which requires further analysis (Fig 3)
A Seasonal variation was found (p>0.05), while no yearly difference was found (p>0.05), with the lowest incidence rate in the winter (Fig 4,5).  
Objectives
The objective of this study is to determine the relationship between pH and temperature and increased incidence rates of Vibriosis in the state of Florida.
Materials and Methods
Weekly data of Vibrio outbreaks in Florida were obtained from Morbidity and Mortality Weekly Report (MMWR) (Table I). Provisional cases of infrequently reported notifiable diseases sub-section was utilized to obtain the weekly incidence rate during
Water quality data, in 15 minute increments, were obtained from the Centralized Data Management Office at the National Estuarine Research Reserve (NERR) (Columbia, SC).
Average weekly temperature data for was retrieved from the Southeast Regional Climate Center through The  National Oceanic and Atmospheric Administration (NOAA)
Introduction
Figure 5. Florida Incidence Rate by Year
The harvest and consumption of raw oysters, shrimp, crabs, and other shellfish in the US Gulf States, is commonplace and deeply rooted in Southern culture.
Ninety percent of the crawfish, 70% of shrimp, and 69% of oysters caught in the United States come from the US Gulf Coast fisheries .
Although considered a delicacy, the consequences of this tradition can adversely affect human health.
Vibrio is a genus of naturally occurring rod-shaped bacteria commonly found in shellfish.
Figure 1: Vibrio
This life-threatening bacterium is found in warm, marine environments, such as the Gulf of Mexico.
According to Centers for Disease Control (CDC), an estimated 80,000 illnesses and 100 deaths each year in the United States are caused by the Vibrio species.
Conclusions
This research provides evidence for the relationship between Vibrio outbreaks, temperature and pH.
The results of this study showed that average temperature is significantly and positively related to Vibrio outbreaks where pH is not.
Overall, our findings predict that, in Florida, illnesses caused by Vibrio are related to temperature, however, other climatic factors must also be examined.
It is hoped that the findings of this research will help guide public health officials as well as seafood industries in order to protect the health of Florida and Gulf Coast residents.
Source
Data Set
URL
MMWR
Vibriosis Incidence Rates
wrmorb.asp
NEER Data Management Office
Water Quality Data
(pH)
ort.cfm
Southeast Regional Climate Center
Temperature Data
Figure 2: Regression Analysis Between Vibriosis and Temperature in Florida y= 0.07x-2.06; R2=0.166.
Table 1: Sources of raw data for Statistical Analysis: MMWR= Morbidity and Mortality Weekly Reports ; NEER= National Estuarine Research Reserve
Acknowledgments
Data Handling
The average weekly pH for 8 locations within Apalachicola and Rookery Bay, FL were calculated from water quality data using SAS 9.4 software.
Next, the overall average weekly pH for all locations including weekly incidence cases, average weekly temperature, and average pH, were compiled onto a Microsoft Excel (Redmond, WA) spreadsheet for export to SAS 9.4.
The project described was supported by NIH-RCMI Grant# G12MD from NIH/NIHMHD and PGA-P from the US Department of State.
Figure 3: Regression Analysis Between Vibriosis and Gulf of Mexico pH y=0.909x ; R2=0.005.